I'm trying to take the extra chainwheel off my recent conversion. I'm using the 42 tooth and ditching the 52 tooth but the chainwheel is swagged to the crank. I don't have a spider or whatever to connect the smaller chainwheel to the crank. Is there something something I can buy or do I have to buy a right side crank or crankset. I was hoping to keep as much original as possible.

Do you have a picture of the setup?

You can grind the teeth off and turn it into a ring guard.

or you could use the 52 ring and remove the 42. just use a bigger sprocket to get the right GI.

i personally think larger chainrings are more astetically pleasing as well.

Sounds like 1 peice cranks from an old ten speed. The bike shop I go to offtered to cut my outer chain off if I wanted. The other solution is buying a new chainring and cranks, leaves you with a nicer look as well.